If I am understanding this correctly you are comparing end game crafting gear vs leveling gear. The artisan gear is harder to get because at the end of ARR is was really good crafting game to craft end game items, if you had level 50 crafters this was the gear you strived to get. People that had this probably used it to level all the way to 60 when HW released because the gear was really good. Now if you started HW withput level 50 crafters or you were level 50 but didnt have good gear, you simply did leves or collectables and obtained leveling gear because it was much easier than obtaining the level 50 end game set.
This is true for all expansion so far, HW had the level 60 ironworks, and when SB released they used ironworks to get to 70 without obtaining leveling gear. But people whi didnt have crafters leveled obtained leveling gear.
SB has its own set, which will likely be used to level to 80 for anyone who kept up with ceafting, but for people who didnt they will use the much easier to obtain leveling gear.